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12.5.2
Synchronous Operation
In synchronous operation, the values in a number of TCNT counters can be rewritten
simultaneously (synchronous presetting). Also, a number of TCNT counters can be cleared
simultaneously by making the appropriate setting in TCR (synchronous clearing). Synchronous
operation enables TGR to be incremented with respect to a single time base. Channels 0 to 2 can
all be designated for synchronous operation.
Example of Synchronous Operation Setting Procedure:
Figure 12.14 shows an example of the synchronous operation setting procedure.
Synchronous operation
selection
Set synchronous
operation
Synchronous presetting
Set TCNT
<Synchronous presetting>
[1]
Set 1 to the SYNC bits in TSYR corresponding to the channels to be designated for synchronous
operation.
[2]
When TCNT of any of the channels designated for synchronous operation is
written to, the same value is simultaneously written to the other TCNT.
[3]
Use bits CCLR2 to CCLR0 in TCR to specify TCNT clearing by input capture/output compare,
etc.
[4]
Use bits CCLR2 to CCLR0 in TCR to designate synchronous clearing for the counter clearing
source.
[5]
Set 1 to the CST bits in TSTR for the relevant channels, to start the count operation.
Figure 12.14 Example of Synchronous Operation Setting Procedure
Rev. 1.00, 09/03, page 332 of 704
[1]
Synchronous clearing
[2]
Clearing
source generation
channel?
Yes
Select counter
clearing source
Start counting
<Counter clearing>
No
Set synchronous
[3]
counter clearing
[5]
Start counting
<Synchronous clearing>
[4]
[5]
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